The kicker is that WiFi adapters can only hear WiFi energy, meaning other WiFi devices such as laptops, tablets, mobile phones, and WiFi cameras. When a WiFi device wants to communicate, it will perform clear channel assessment (CCA) to determine whether the shared medium is busy - basically, seeing if any RF energy is detected. It boils down to the limitations of WiFi adapters they’re unable to demodulate non-WiFi signals. a dedicated analyzerĪ common question regarding spectrum analysis is why can’t the built-in, or USB, WiFi adapter be used for spectrum analysis? Some transmitters hop on different frequencies while Bluetooth looks different from a cordless phone, which looks different from a video transmitter.īuilt-in WiFi card vs. In addition to the shape of a signal, there is also a pattern. For example, 802.11g ERP-OFDM appears very differently than 802.11b. More specifically, you want to take note of its shape. Other things to note are the RF characteristics. If it’s communicating often, the duty cycle will be recorded and the signal begins to appear red in color. When you are close to the source of interference, it will begin to show itself on the application. When searching for an interfering transmitter, we are looking for a number of characteristics.ĭensity is an easy identifier. What exactly are we looking for on a spectrum analyzer? The analyzer will pick up all signals on the 2.4 GHz and 5 GHz frequencies. The closer an engineer gets to the interfering source, the amplitude increases on the application and is indicated, usually, in red. This is why the directional antenna is used to help pinpoint the location of the interference. The process is not easy as the engineer has to distinguish the noise from other valid signals. The application will measure the area and plot the interfering signal pattern on the screen and along with its strength. To find the source of interference, an engineer uses directional antennas in conjunction with the spectrum analysis application. Various kinds of interference corrupt WiFi signals. Spectrum analysis can help optimize a WiFi network by finding the interfering transmitter. After deployment, spectrum analysis determines whether interference exists and engineers often use it for troubleshooting when a WLAN is performing poorly.
An engineer can find the interference and either remove it or design around it. WiFi spectrum analysis is performed throughout the WLAN lifecycle. Before deployment, spectrum analysis finds interference that may affect a wireless deployment. In addition to seeing that strength, a spectrum analyzer can find interference that would negatively impact wireless performance. One of the key steps that a WLAN engineer can take to improve WiFi performance is to conduct spectrum analysis, which is a method for visualizing the radio frequency in a surveyed area and determining the strength of a signal.
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